They've been getting a few now. This coast usually spits out M8's, with the capability for a doozy M9. The last big Mexico City earthquake was around here. That basin is deep soft soil inside a soft rock basin. It is capable of amplifying PGV by a 100 times. Of course, it doesn't amplify PGA, so nobody cares. :( It's just one of those many cities with zero seismic capacity, with the same odds for a big earthquake. Most likely the next big earthquake won't be here.